I noticed that there are several different threads about people counting, but what hardware is the best to use?
I have thought of:
witch I guess does not need a mirror/reflector on the other side. Is this correct?
Ultrasonic distance sensor.
IR sensors, but most of the ones I have looked at have limited range and I don't understand if I need a reflector.
PIRs If you paint the lens black and only leave a small hole I would guess it should behave almost like a beam at a short distance. But It looks like they all have long "reload times" so I think that they are not the best option for this.
Are there any other sensors that would be a good option for counting people walking in both directions ?